Population Ecology & Distribution of Organisms – Key Vocabulary

A comprehensive set of vocabulary flashcards covering key terms and concepts from Chapter 40—Population Ecology and the Distribution of Organisms—focusing on ecological hierarchy, climate influences, biomes, population dynamics, growth models, life history strategies, and regulatory mechanisms.

Ecology

The scientific study of interactions between organisms and their environment, encompassing biotic and abiotic factors.

Organismal Ecology

Sub-discipline focused on how an individual’s structure, physiology, and behavior meet environmental challenges.

Population Ecology

Branch of ecology that analyzes factors affecting population size and how and why it changes over time.

Community Ecology

Study of interactions (predation, competition, mutualism, etc.) among populations of different species in an area.

Ecosystem Ecology

Investigation of energy flow and chemical cycling between organisms and the physical environment in a community.

Landscape Ecology

Examination of exchanges of energy, materials, and organisms across multiple, connected ecosystems (landscapes or seascapes).

Global Ecology

Study of how the regional exchange of energy and materials influences organism distribution and ecosystem functioning across the biosphere.

Climate

Long-term, prevailing weather conditions—particularly temperature, precipitation, sunlight, and wind—in a given area.

Terrestrial Biome

Major life zone on land, characterized by dominant vegetation type and specific climate patterns.

Aquatic Biome

Major life zone in water, defined primarily by physical and chemical environment such as salinity, depth, and flow.

Photic Zone

Upper aquatic layer where light is sufficient for photosynthesis.

Aphotic Zone

Aquatic layer below the photic zone where little or no light penetrates.

Pelagic Zone

Open-water region of an ocean or lake, including both photic and aphotic zones.

Benthic Zone

Bottom substrate of aquatic environments, consisting of sediments and inhabited by benthos organisms.

Littoral Zone

Shallow, well-lit waters near shore in a lake; supports rooted aquatic plants.

Limnetic Zone

Deeper, open water in a lake too far from shore for rooted plants; dominated by phytoplankton.

Thermocline

Narrow, horizontal layer in water bodies where temperature changes rapidly with depth, separating warm upper and cold deeper water.

Dispersal

Movement of individuals or gametes away from their area of origin or centers of high population density.

Abiotic Factor

Nonliving chemical or physical component of the environment (e.g., temperature, water, sunlight, soil).

Biotic Factor

Living component of the environment, including other organisms that influence distribution and abundance.

Population Density

Number of individuals per unit area or volume of habitat.

Dispersion (Clumped, Uniform, Random)

Pattern of spacing among individuals within population boundaries: aggregated, evenly spaced, or unpredictable.

Cohort

Group of individuals of the same age followed from birth until all are dead in demographic studies.

Life Table

Age-specific summary of the survival and reproductive rates of individuals in a population.

Survivorship Curve

Graph showing proportion of a cohort still alive at each age; classified as Type I, II, or III.

Type I Curve

Low mortality in early/mid-life with steep increase in death rates among older individuals (e.g., humans).

Type II Curve

Constant death rate over an organism’s life span (e.g., some birds, rodents).

Type III Curve

High early mortality with survivors living relatively long (e.g., oysters, many plants).

Intrinsic Rate of Increase (r)

Per capita rate at which an exponentially growing population increases in size at each instant in time.

Carrying Capacity (K)

Maximum population size that an environment can sustain indefinitely.

Exponential Population Growth

J-shaped population increase under ideal, unlimited resource conditions; described by dN/dt = rN.

Logistic Population Growth

Population expansion that slows as size approaches carrying capacity; modeled by dN/dt = rN(K−N)/K.

Density-Independent Factor

Birth or death rate influence that does not change with population density (e.g., drought, temperature extremes).

Density-Dependent Factor

Regulatory mechanism whereby birth rates decline or death rates rise as population density increases (e.g., competition, disease).

Life History

Traits affecting an organism’s schedule of reproduction and survival, including age at first reproduction, frequency, and offspring number/size.

Trade-Off (in Life History)

Allocation compromise between survival, reproduction, and offspring quality due to limited resources.

r-Selection

Natural selection favoring high reproductive rates in uncrowded environments; maximizes r (intrinsic growth).

K-Selection

Selection favoring traits that enable organisms to survive and reproduce at high densities near carrying capacity (K).

Metapopulation

Group of spatially separated local populations linked by immigration and emigration.

Ecotone

Transitional area where different biomes or ecosystems merge, often with high species diversity.

Population Dynamics

Fluctuations in population size over time and space resulting from complex biotic and abiotic interactions.

Territoriality

Defense of a bounded physical space against other individuals, often leading to uniform dispersion patterns.

Thermoregulation (Temperature Limitation)

Effect of environmental temperature on biological processes, influencing species distribution.

Logistic Growth Curve

S-shaped graph showing how population growth rate slows as carrying capacity is approached.

Exponential Growth Curve

J-shaped graph depicting constant per capita growth and accelerating population size under unlimited resources.